A321534 a(n) gives the number of configurations of non-attacking rooks up to symmetry on an n X n chessboard such that the number of distinct directions between the rooks is given by A321531(n).
1, 1, 1, 1, 2, 21, 11, 74, 89, 18
Offset: 1
Examples
For n = 5, the a(5) = 2 essentially different configurations of nonattacking rooks with the maximal number of directions between them are given by the following two chessboards:
+---+---+---+---+---+
5| X | | | | |
+---+---+---+---+---+
4| | | X | | |
+---+---+---+---+---+
3| | | | X | |
+---+---+---+---+---+
2| | | | | X |
+---+---+---+---+---+
1| | X | | | |
+---+---+---+---+---+
A B C D E
+---+---+---+---+---+
5| X | | | | |
+---+---+---+---+---+
4| | | | X | |
+---+---+---+---+---+
3| | | X | | |
+---+---+---+---+---+
2| | | | | X |
+---+---+---+---+---+
1| | X | | | |
+---+---+---+---+---+
A B C D E
Comments